The Cummins ISL is a straight-6 diesel engine designed and produced by Cummins. It is 8.9 liters in displacement, and went into production in 1998. The engine was based on its 8.3 liter predecessor, the Cummins C8.3 engine.

The ISL is not to be confused with the older L10 series, which Cummins had produced and sold from 1982 to early 1998. The old L10 series, which like the current ISL, had seen use in the applications listed above (plus, early Dennis double decker buses), displaced 10.0 liters, was slightly larger, and had been replaced by the M11 entirely in 1994, although the natural gas version, known as the L10G, had hung on until the spring of 1998.

The Cummins ISL also has a sister engine which is based on the existing ISL 8.9-liter block which runs on compressed natural gas called the L Gas Plus.

By late 2003, Cummins announced that they will revise the engine to sport a High-Pressure Common-Rail (HPCR) system to help with emissions and also a variable geometry turbocharger system to help with the performance on this engine.

To meet EPA 2007 regulations a particulate filter was made standard and a crankcase coalecing filer was added to control crankcase emmission. Durring the phase in period between 2007 and 2009, Cummins will produce 50% of their engines to meet EPA 2010 regulations. To meet EPA 2010, the ISL will use selective catalytic reduction to reduce nitrogen oxides.


  • ISL 250
  • ISL 280
  • ISL 330



Current Products

Diesel ISB - ISC - ISL - ISM
CNG B Gas Plus - ISL G
Propane B LPG Plus

Former Products

Diesel B5.9 - C8.3 - L10 - M11 - VTB-903
CNG B5.9G - C8.3G - L10G - C Gas Plus - L Gas Plus